Conventionally, a semiconductor package structure including a semiconductor device such as an IC chip or the like mounted on a support substrate is known. Generally in such a semiconductor package structure, a semiconductor device such as an IC chip or the like is bonded to a support substrate via an adhesive material called a die attach material, and the semiconductor device is covered with an encapsulation material (formed of a sealing resin) for protection.
As the support substrate for the semiconductor package, any of various types of substrates including a printed circuit board, a ceramic substrate and the like is used. Especially recently, semiconductor packages using a metal substrate have been actively developed. A semiconductor package using a metal substrate has advantages of being high in electromagnetic shielding properties and thermal characteristics, and is now a target of attention as a highly reliable semiconductor package.
However, a metal material and a resin are significantly different in the coefficient of thermal expansion (CTE). Therefore, there is a problem in the production of a semiconductor package using a metal substrate that an internal stress is caused due to the difference in the coefficient of thermal expansion between the metal substrate and an encapsulation material (formed of a resin used to protect a semiconductor device), resulting in a warp of the encapsulation material (Japanese Laid-Open Patent Publication No. 2010-40911).